The juvenal plumage appears first on the back and scapulars, then on the breast and wing coverts. A bird in my collection, about half grown has the above parts well feathered and the remiges one-third grown; but the head and rump are still downy and the rectrices have not yet started. The juvenal plumage is like the adult, except that the buff edgings of the feathers on the sides of the back and the scapulars, forming the stripes, are narrower and paler, sometimes almost white on the outer webs. The body feathers and some of the scapulars and tertials are molted during the fall, making the young bird almost indistinguishable from the adult.
Both young birds and adults have a partial prenuptial molt in the late winter and early spring, involving the contour feathers, wing coverts, tertials, and the tail. Adults have a complete molt between July and October. The spring and fall plumages are alike except that the fresh fall plumage is somewhat more richly colored.
Food.—The feeding habits of the Wilson snipe are much like those of the woodcock, except that it often feeds in much wetter places and is somewhat less nocturnal. Benjamin T. Gault (1902) discovered by observation that snipe occasionally resort to open mud flats, unmindful of the cover of darkness and that they feed at all hours of the day. He describes their method of feeding as follows:
The snipe seemed to select as special feeding grounds the water line just bordering the flats, where the mud was soft and into which they delighted in sinking their bills to the fullest depth. And in withdrawing them they never elevated their necks in true sandpiper style. On the contrary they kept their heads well "chucked down," so to speak, and in moving about from place to place, which they seldom did, however, continue to hold them in the same fashion.
In some respect their probing methods resembled the rooting of swine—a simple, up and down forward movement, and if remembered rightly, without lateral twists or side thrusts of any kind, and at times exposing fully one-half of the bill.
Whether the Wilson snipe actually do resort to the so-called "suction" method of procuring their food is a question still undetermined in my mind. The glasses however brought out the important information that the probing or feeling movements of the bill were accompanied every now and then with a guttural or swallowing motion of the throat, which at times developed into a decided gulp, as though large morsels of some kind were being taken down, and this without the removal of the bill from the muck.
Henry W. Henshaw (1875) describes an entirely different method of feeding; he says:
In migrating, however, especially in Arizona and New Mexico, did it depend wholly upon its usual methods of obtaining sustenance, it would fare badly, since, in some sections, there is a total lack of meadow and marsh, and then it may be seen in broad midday running along the sandy borders of the streams, and picking up from among the pebbles and débris any tidbits in the shape of insects it can find. It retains, however, even under these adverse conditions, its habit of squatting, and, when approached closely I have seen it lower its body close to the ground, shrink as it were into as little space as possible, and so remain till I was within a few feet, when it would get up with its well known scaip, scaip, and, following the turns and sinuosities of the streams, endeavor to find some little covered nook into which it could drop out of sight.
M. P. Skinner watched a snipe feeding on the muddy shore of a pond in the Yellowstone Valley; he says in his notes:
He was about 6 inches from shore and at each stroke his bill went in up to his eyes. The strokes were rapid like those of a woodpecker. He covered a space perhaps 4 inches wide and 15 feet long in an hour, getting something every half dozen strokes or so. He was very busy there for two hours at least.
Earthworms probably constitute the principal food of the Wilson snipe, but it also eats cutworms, wireworms, leaches, grasshoppers, locusts, beetles, mosquitoes, other insects and their larvae, and some seeds of marsh plants.